Warning: it may contain spoilers for season 4
It is Elsa that helps her make the decision – or rather, make her realize that she decided a long time ago, back when Henry's words ripped her already battered heart apart. She just needed an opportunity, a push that will overcome foolishly remaining doubts and hopes.
At first she planned to cross the townline and move to one of those great big cities – to a place as different from Storybrooke as possible. To a place where every little thing would not remind her that noone ever will choose her for herself, that she will be never enough, worth fighting for. As far away as possible from the town where every person sees her only as a sum of her mistakes, a walking danger, a bomb that could go off any minute and destroy everything they hold dear, where the best she could be for them is absent – not dead, because that would taint their precious souls, just nonexistent. It is not like she does not understand that. Who in their right mind would want meeting the infamous Evil Queen while doing shopping or drinking in a bar? Still, there was a time when she believed she could put the past behind her, a stupid thought that saving everyone more than once would mean that there is a hope for happy ending even for her.
She still remembers the sheer joy and overwhelming love she felt that day at the docks. Putting the last touches to the nearly finished book, she saw the scene clearly before her eyes: Henry's eyes, so happy, so full of unconditional love, the kiss that made her believe she was the mother he always wanted, his meeting with Robin… It was the talk that happened right after which gave her an idea to move. She wanted to see all to things her son was talking about, experience life he had there – and later she thought it could be the only thing that she would allow to connect her to a life she left behind. But as she started to make preparations – not that she would admit it to herself at the time; then, it was just an idea which was helping her to focus on issues connected with Elsa's arrival – she realized she would not be granted even that comfort. Her usual responses to heartbreak were not exactly rational and thought through so in a strange way she was glad that at the time she was just too numb to act. Then she would leave a son with a feeling of guilt and betrayal at the same time for a place where she did not have any reasonable ways to support herself or even get around, not in the long run.
The clock strikes three and she realizes she spent almost whole day on that book. As if it really needed it. She started on it a few days ago and normally she would have finished it already but she recognized easily what was holding her back - the foolish emotion she could not completely rip out from her heart. Hope. Hope that maybe… Maybe… But Henry called her only once and the whole conversation was about an amazing time he was having with the Charmings, all the new tricks he learned from 'Killian', that 'Mom' finally starts to grasp the general idea of proper baking... She concludes she should be glad. This is exactly what she was aiming for when she made her decision but a selfish part of her wished that Henry would see her through. The True Love kiss cannot lie, can it? True Love is the most powerful magic of all. At the time she believed it with her whole heart. Her then naive, innocent, pure heart. But now she knows better. With True Love Kiss you can break any curse but it will not grant you a happy ending. But now I have a chance to provide it to Henry. And this is all that matters.
She takes the book and her purse. She could probably try to use magic but it was still unpredictable at times, not dark but not light either. Resembling her heart, she thinks. And that is another choice she stands before. After defeating Zelena she thought she could embrace that change, she was more than ready for it. For one perfect evening she believed she could have it all – love, happiness, forgiveness. Family. Second chance. Moments later everything came crashing down.
Walking through the city is quite an ordeal these days. Even though she tries very hard not to, sometimes she gets a glimpse of Robin – with his son, alone or with Her. It is a relief, really, that he never approaches her on those occasions. The other ones were enough and as heartbreaking as it gets. She takes comfort in the fact that in a few days all of this will not matter. She will hopefully find peace.
It is time to set things in motion. And she knocks on Dr. Hopper doors.